<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>js的三种引入方式</title>
</head>
<body>
    <input type="button" value="提交" onclick="alert('haha')">
    <!-- <script>
        alert('haha')
    </script> -->
    <script src="js.js"></script>
</body>
</html>